Non-woven filamentary products and process



1959 H. ,G. LAUTERBACH EI'AL NON-WOVEN FILAMENTARY PRODUCTS AND PROCESSFiled Oct. 31, 1956 INVENTORS G. LAUTERBACH HERBERT -HARRY-M.

BY Q7 2'. (3M

NORTON ATTORNEY United States Patent O NON-WOVEN FILAlVIENTARY PRODUCTSAND PROCESS Herbert G. Lauterbach and Harry M. Norton, Wilmington, Del.,assignors to E. I. du Pont de Nemours and Company, Wilmington, Del., acorporation of Delaware Application October 31, 1956, Serial No. 619,46918 Claims. or. 28-72) This invention relates to formation of continuousfilamentary material into non-Woven coherent pliable feltlike articles.7 p Felting of wooland fur represents the oldest method nizedunsuitability of continuous filaments for similar processing, althoughrelatively stiff and brittle articles can be formed from batts ofcontinuous filaments by bonding of the filaments, as by fusion or use ofan adhesive.

It is also know that'acrylonitrile polymer fibers do not felt well evenin wool blends because of their stiffness. To prepare a good felt fromacrylonitrile polymers or copolymers in blends with wool (50/ 50 orhigher proportions of acrylonitrile polymer fiber) it is necessary totreat the blends with about aqueous sodium thiocyahate solution atabout90" C. before felting.

Oneobject of this invention isto provide a non-woven Coherent pliableunbounded (i.e., unbounded and unadhered) felt-like article comprisingpredominantly syn- .thetic organic continuous filamentary material, saidarticle being characterized by predominantly coplanar orientation of thefilamentary components in superimposed layers with portions of some ofthe filamentary components from each layer oriented into at least one-adj-acent layer. 1 *Another' object of this invention is toprovideanonwoven coherent pliable felt-like article comprising retractablepredominantly synthetic organic continuous filamentary material; also,the retracted article obtainable therefrom.

Another'object of this invention is to provide processes a for producingthe above described articles. I Other objects of this invention,together with means "and methods for obtaining them, will be apparentfrom the following description and the accompanying diagrams. g

The felt-like articles of this invention resemble wool felts except forthe different structure of the article and composition and character ofthe-filamentary material.

The structure may be distinguished' by the presence of superimposedlayers of a preponderance of synthetic organic continuous filamentarymaterial, portions of which are oriented into at least one adjacentlayer of filamentary material, that is, portions of some of thefilamentary material are oriented in the thickness direction of thefelt-like article. The oriented filamentary material does notdetractfrom the utility of the felt-like article butactuallylsubstantiafly reinforces the article and particularly-sobecause the filamentary material'is unfused'an'd unbonded and eachfilamentjs free tomotve over a'djacent filaments, thereby impartinggreat flexibility to'the 1 to this invention.

2,938,064 Patented Oct. 13, 1959 2 article. The felt-like articles ofthis inventionare easily distinguished from felted products containingthermo- .plastic fibers which have been bonded together by coating orimpregnating with resins or heated until many of the filaments are fusedtogether. In bonded articlesof this sort the adhered fibers are not freeto move relative to one another, and these resin-treated or heat-bondedproducts are stiff and undesirable for many applications where thestrong pliable long-wearing felts of this invention may be used toadvantage.

Q The invention will be understood more readily by reference to thedrawings. V Figure l is a schematic representation of apparatus usefulin this invention.

" Figure 2 is a fragmentary perspective view showing filamentarymaterial arrangement when first assembled into a loose batt.

' Figure 3 is a similar fragmentary perspective view showing theappearance of the batt of Figure 2 after portions of some of thefilamentary material have been forcibly oriented by needle-punching. Theupper and lower (horizontal) surface areas of the needled batt of Figure'3 are slightly less than that of the loose batt of Figure 2, but thethickness of the batt of Figure 3 is slightly greater than the thicknessof the batt of Figure 2. "Forcibleorientation of portions of thefilamentary mafterial results in contraction of the surface areas normalto the direction of needling of the batt and a slight increase in thethickness of the batt. I

Figure 4 shows the appearance of a batt comprising retractablepredominantly synthetic organic continuous filamentary material aftersome of the filamentary material has been first forcibly oriented byneedle-punching and then treated to retract the filamentary material.The batt is substantially more compact than an unretracted batt, andthehorizontal surface area of the needled, retracted batt is less than thatof the batt prior to retraction. The thickness of the batt is usuallyslightly greater than the thickness of the unretracted batt.

Figure 5 shows a similar batt after forcible orientation I of portionsof some of the filamentary material, retraction and pressing. Pressingdoes not change substantially either the horizontal surface area or thebatt strength.

In the apparatus shown in Figure 1, movable belt 11 supports filamentarymaterial being processed according Superimposed layers of filamentarymaterial 12 are deposited on the belt by hand or mechanical means, asdesired, for transport through needle loom 13 which reciprocates needlesinto and out of the looselayered batt of filamentary material, forciblyorienting portions of some of the filamentary components into at leastone adjacent layer and preferably into a position substantiallyperpendicular to the faces of the batt. Needle-punching results incontraction of the surface areas of the batt normal to the direction ofneedling, and the needle-punched batt at 14 is shown to have smallersurface area than that of .the loose layered batt prior to needling. Theneedle-punched batt at 14 may be used without further treatment and ishighly useful in a number of applications. A needle-punched batt ofpredominantly retractable filamentary material optionally may bepassedthrough oven 15 to further compact the batt and increase itsdensity by retracting the filamentary material. Retraction of ,the ,battas by heating to, suit able temperature results in further reduction inthe upper surface area of the batt, as shown at 16. Optionally, also,a'retracted or unretracted needle-punched batt may be pressed bypassing through rolls 17 which forwardthe batt to, a collection point.Roll pressurernay beadjusted to-compress the strip to, slightly reducedthi ckness, if desired. i

In generalgtli'e objects erthe'bi-"e'sm invention neat;

complished by forming a loose layered b'att of predorni inantlysynthetic organic continuous filamentary material, the layered batthaving substantially parallel top and bottom faces with predominantorientation of thecomponent 'filamentarymaterial parallel to thefaces of;the batt, and forcibly orienting, portions of some off the filamentaryjcornponents into at least one adjacent layer of filamentary material,preferably into a position substantially perpendicular to the faces ofthe batt, to produce a coherent non-woven felt-like article of unbondedfilamentary materiaL HThe invention extends to exposure of sucharticles, 1n WhlCh at least part of the component filamentary materialis characterized by a capacity for retracting (that l is, shortening, asby crimping or shrinking, upon being heated or otherwise suitablytreated), to conditions effective to retract the retractable filamentarymaterial, whereupon the batt becomes even more compact while remainingunbonded and felt-like; Thus, this invention contemplates as a;principal product a non-woven'coherent feltlike article of unbondedfilamentary material'containing apreponderance of synthetic organiccontinuous filamentary material, in which portionsof some of thefilamentary material are oriented in the thickness direction of the'batt. The phrase ,predorninantly synthetic organic con- ,tinuousfilamentary'material as used herein refers to filamentary material morethan 50% of [which possesses gan'ic,'and continuous in character.

essentially three properties, namely, it is synthetic, or-

' Coherent non-Woven unbonded felt-like'articles may be prepared inaccordancewith this invention using all unretractable filaments but inaccordance with a preferred embodiment part of the; filamentary materialused has the ability to retract when properly treated, as with'heat or aswelling agent. The retraction may result from a simple reduction inlength (that is, shrinking) or from a distortion of the filament into anirregular shape asby crimping or curling or'both The retractability ordegree of retraction refers to a free filament at the treatingconditions and is expressed conveniently asthe percent decrease (basedupon the original value) in shortest distance between-two points on'anindividual filament; thus,

' when both shrinking and crimping occur, his a summation of the effectproduced by diminution in length and assumption of a more irregular pathbetween the points of measurement. In some instances, it is gdesirableto prepare articles in accordance with this invention composed entirelyof retractable filaments. Materials not retractable under the conditionsof treatment can be blended with retractable syntheticfilamentary'mfaterial or layered with it in orderfto achieve-specialeffects,

Thus, glass filament which exhibits zero retractability and/or woolfibers which are essentially'not retractable may be blended witha'predominant proportion of synthetic organic continuous filaments. 7

All synthetic organic continuous filamentary material can be utilized inthis invention and, where it is desired to produce a retracted product,practically all synthetic polymeric filament-forming compositions can bemanufactured r so as to have the necessary retractability. In additionto those exemplified hereinafter, these polymers include polyamides(e.g., 'polyhexamethylene adipamide, polyhexazmethylene sebacamide,poly-epsilon-caproamide, and

copolymers of these or other polyamides),lpolyjesters (e.g.,polyethylene terephthalate, polyethylene sebacate), polyesteramides,.polyureas, polyurethanes, acrylonitrile polymers (including copolymersof acrylonitrile, especially with other ethylenically unsaturatedmonomers, a,

such as vinyl chloride, vinyl acetate, methyl acrylate, and vinylpyridine) vinylpolymers generally (e.'g., polyvinyl acetate,polyvinyl'chloride, and polystyrene), polymerized fluoroolefins (e.g.,polytetrafiuoroethylene, 'polytrifluoro monochloi'oethylene,polyhexafluor'opropylene') polymer 'ja'cent layers.-

or mechanically by feeding them onto a collecting surface] where theyaccumulate in overlapping layers, the individual filamentary componentsin each layer being predominantly coplanar, lying parallel to thecollecting surface and to the bottom and-top of the batt so formed.-Conveniently, the step of batt formation will be accomplished bymechanical means, such as forwarding jets, which may be operated to laythe filaments down at random or in some desiredpattern; The collectingsurface -may be rotated-or; oscillated ,to promote even accumulationoflthe filamentsga moving belt used as the collecting surface also canconvey the'formed loose layered batt tothelocation where portionsof'some of the component filaments Will be oriented forcibly to aposition substantially'pe'rpendicular to the faces of the batt. a i iDepositing filaments with fluid jets permits formation of batts byelimination of blending procedures, and-generally simplifies handling ofstarting materials. Italso facilitates the use of continuous monoormultifilaments,

' or continuous lengths of spun staple yarns in the preparation of thebatt. V Heretofore, use of continuous filaments in felt structureshasbeen confined to woven backings or cores. Synthetic filaments areinitially produced as continuous filaments, and use in this formsimplifies the manufacturing operation. The use of continuousfilamentsimparts added compactness and 'strengthtoi'the product, whichmay range from a soft pliable to'a hard Stlfi fClt. v y I l 1',

Regardless -of how the batt is formed, or the type of continuousfilamentary materialused (e.g., bulked yarns, monofilament ormultifilament 'yarns either twisted: or untwisted, rope, tow, thread,ribbon, spunstaple'yarns,

braid, etc.), the batt'will ordinarily havelbeenbuilt up a gradually bysuperposition of a number oflayers ofi-r'naterial. The resulting battconsists initially, of a loose,

fluffy mass in which filamentary components -rnay be oriented in layersusually in planes parallel to'thel belt or other surface on which thebatt is formed; l f

'The linear azimuthal orientation of the layers 'of filaments in anyloose batt may be random or may be. prey determined to any azimuthalangle. Preferably, the ,fila-I -mentary components of adjacent layersliejatanazi muthal angle of between about 45 and to onesana other andmost preferably are oriented 90 from one an:

other. Desirably, adjacent layers of filamentary compoi nents will havean average difference in azimuthal linear orientation of at least 5.

For example, a batthaving random orientationwill have fan averagedifference of about 45? in azimuthal linear orientation between ade out!These filamentary components will remain oriente n layers moreor lessparallel to the faces of the final prodnot unless some way is found tocause them tointerlock between, layers. A surprising feature of thepresentwinvention is thejdiscovery that a coherent strong, pliablenon-woven felt-like product having exceptional proper:

ties is obtained even when -relatively sm-allj numbers; of

thefilaments have been reoriented byneedle-punching so that portions ofthe filaments'are positione'dlin atileflst two layers offilaments. 1

V 'rhe preferred method of achievingthe required o r'ientas tionoffilamen ts in the batt is needle-punching," which'gisconvenientlyaccomplished in a conventional-needl loomt ized hydrocarbons(elg, polyethylene) and halogenated derivatives thereof, syntheticproteinaceous polymers, and t Such a loom has a large number ofclbselyspaceda'ral rocatingneedles designed to tchr dra'g-"fila Thefilamentary mentary material as the needles move into the batt. Relativemovement between the batt and the needling location may beeitherintermittent (while the needles are drawn clear of the batt) orcontinuous. To maintain the dimensional stability of the batt duringneedle-punching, it isusually advisable to feed simultaneously to theneedle loom a supporting layer, for example, a layer such as acheesecloth, a film, or a warp of the. same fibers as in the batt. Thesupporting layer may be readily stripped after thepunchingoperation, orif of. the same fiber composition may'b e retained in the punched batt.This type of loom 'iswellknown for use in textile operations, so furtherdescription is unnecessary. {Of course, other suitablehmeansmay be. usedfor forcibly orienting filaments into-thedesired position; for example,the batt may be hand-punched with an instrument elfective to orient oneor more filaments from the surface toward the interior oflthe' beitt,but such 'a procedure is quite tedious, of

course. t

. jProducts formed by needle-punching loose batts according to:this'invention have many of the desirable characteristics ofwool felts',despite structural dissimilarities observable upon close inspection. Nodifiiculty is encountered in're'aching and even exceeding in many casescustomar'y' felt densities in these articles. They are readilydistinguishable from non-wool felt-like productscontaining-thermoplastic filaments bonded by heat or adhesivestoione-another' because of their superior pliability and higher. splitstrength compared with therelatively stifif -unyielding. character andlow split strength of bonded structures. In tensile strength, theproducts of the present invention comparevery favorably with propertiesof conventional felts and felt-like products, including those made. fromsynthetic staple fibers.

-The. rather fuzzy surface of the product can be smoothed by pressing. Aheated pressing surface may induce retraction of surface filaments, butthe temperature should bemaintained below the softening temperatureof-the. fiber to prevent fusion. This added compacting treatment" is notessential in the majority of uses, nor need the product be subjected toany equivalent of fullingL-z: The initial conditions of batt density andthe intensity: of treatment can be chosen to produce practicallyany-desired density and .coherencein the product'without necessity forany rubbing pretreatment or fulling aftertreatment. 1; The. practice ofthis invention is exemplified below in some detailr. In all theexamples, physical characteristics ofthe-articles mentioned weredetermined (unless otherwiseindicated) according to recognized felttesting methodsro'f the American Society for Testing Materials,specificallyiASTM-D-.-46153;

. W V EXAMPLE 11 ,Polye thylene terephthalate is melt-spun from flakesby theprocess described by Hebeler in Patent 2,604,689 into: continuous'filaments of 3 denier each. A conventionaLtow-forwarding jet passes abundle of filaments through an air diflfuser, which opens up the bundle,then ontoa cylindrical roll. The roll is rotated slowly andmultifilament yarn is traversed back and forth the 'widthof the ,roll sothat it winds in a helical configuration andthe filaments in adjacentlayers cross at an angle of at least about 5-. After several minutes,the winding isdiscontinued ,andj the accumulation of yarn on the roll;is removed by cutting along the surface of the roll Pi? loosebatt of,filaments. Batt length is equivalent to the circumference of the rolland width is about the same as ;.,the; roll wi dtl 1 The. batt is passedthrough a needle loom :andjneedl'ed' alternately from the top and bottomforza-totalzofll6 times, (8 times per face of the batt). Eachpass-through'the loom results'in. 120 needle penetrations'ipcr squareinch ofbatt surface, a total of 1920 perietiations for the 16 passes. Asa result of the neel. to;the roll axis. This forms a layered non-wovendling, the face of the batt contracts and the thickness increases.Density (areal) of the felt is 32 oz./ sq. yd. The product surfaces arequite smooth, showing only slight indentations produced by theneedle-punching, and lack-; ing any visible recurrent pattern oforientation of the component filaments in azimuth. No needle-formed channels are apparent. The product has a high tensile strength but ispliable'enough to be bent easily by handabout a sharp corner withoutnoticeable separation of filaments.-

EXAMPLE II Continuous multifilaments of crimpable polyethyleneterephthalate retractable to the extent of at least about- 15% areproduced by extrusion through a 34-hole spin neret and drawing by an airjet to approximately 3 denier per filament as disclosed by Hebeler inPatent 2,604,689. The filaments are blown apart by the jet and depositedunrelaxed in a perforated basket with the random assemblage accumulatesto a depth of 1.5 inches. The specific gravity of the batt-like mass isabout 0.01. Needle-punching the batt with a needle loom equipped withregular barbed needles (15 x 18 x 2-5 x 3 /2) results in 50 needlepenetrations per squareinch of batt surface. After needle-punching oncefrom the topvof the batt, it is turned over andrun through the needleloom again to punch it from the other side to give a specific gravity ofabout 0.11. The article so produced is a-co'} herent non-woven pliablefelt-like product, suitable asa filter, of smaller face-surface area andslightly greater thickness than the batt prior to needling.

Immersion of the batt in boiling waterfor 2 minutes results in furtherretraction of the filaments and reduction of the area; of the batt byabout 25%, producing an even more compact felt-like mass. Upon tensiletesting (Instr on) of a 2-inch strip of the retracted product, a forceof about 40 pounds is required to break it, corresponding to about 265lbs/sq. in., at breaking elongation of slightly over l00%. The sameforce is necessary to break a similar strip. taken transversely to theone just tested. This article is particularly useful as a filter forliquids. f In the following examples the batts were" prepared fromcontinuous multifilarnents collected onto a moving belt in overlappinglayers in each of which the filaments were oriented; at ,45 9' to thedirection of belt movement, being oriented at aright angle to oneanother in alteri-v nate' layers. This can be accomplished bymeans ofde,-: liveryjets oscillating diagonally to the belt; however; theapparatus actually used comprised a rotating hollow shaft through whichthe yarn was passed and delivered onto two vertical screwsthat supportedthe yarn in an elongated oval and then dropped it on thebelt, being theapparatus shown in Figure 10 of 'a patent application filed by D. S.Adams and I. F. Bowling on September 10, 1954, as- Serial-No. 455,192,and described in their specification. Y A l EXAMPLE III 'Ar-batt 30inches wide is constructed from 400 denier, 60. filament yarn composedof polytetrafluoroethylene on, a moving belt with-the filaments inalternate layers oriented at a linear azimuthal angle of about alongdiagonals of the belt as just described. The battiS, punched twice on 'astandard plateetype needle .loom (Hunter Machinerr Company) usingregular 1 barbed needles (15 x 18 x 25 x 3 /2) so thatthe'batt receives1 20 penetrations gper: square inch during each pass through the loom.The-batt is folded double and punched 5 additional times under the sameconditions, alternately from. each side. .The batt then is doubledagain. and punched .an additional 15 times, alternately from'; eachside,:.withzthe same punching frequency as beforeuri'llhebatt,-contracted about 13% ,duringthe needling ancl was-converted toafelt-like product weighing 73. lbsAsq. yd which .isxusefuliasya filterfor liquids,

during each pass. 7 ing the needling, resulting in a felt-like articleWeighing especially corrosive fluids. to which ordinary filtercloths arenot. resistant. j .1 ;.'.Duplication of the above procedure withhighly;drawn} (7 times) polytetrafluoroethylene filaments produces'a similarfelt-like article that can be compacted further; by heating to atemperature of about 300C to -produce' a retracted but still unbondedpliable felt-like article. This product is particularly useful as afilter or as a. seal-' ing gasket.

EXAMPLE IV .A batt of continuous nylon (polyhexamethylene adipamide)vmultifilament of 840 total denier'and 140 filaments with layerorientation as in Example III is punched 3 times from the same side togive a total nee dlingfrequency of 90 penetrations per square inch.Theneedled batt is. plied 3 times and punched once from eachside at aneedling frequency of120 penetrations per square inch during each pass.The 3-ply Structure is then.

7 tripled again to a total thickness of 9 pliesand punched 10 additionaltimes, alternately from each side at a needling frequency of 120penetrations per square inch during each pass. A coherent felt-likearticle "useful as a polishing felt for glass results, having a densityslightly in excess of the values for an SAE F-l wool. felt and aretracted needle-punched synthetic staple felt but with strength greatlysuperior to both, as indicated in the following table. The nylon felt ishard and relatively stiff.

Table I I Strength I a p .Weight Felt Density (lb./sq.. Tensile (rt/ c.)yd.) Split (lb./in.

. (lb./2 in. of width Width) per lb./ q Y Example IV .43 7.6 48' '190Polyethylene terephthalate retraeted.. .37 6.4 45 99.3 SAE F-1 wool 347.6 83 31. 3

Tensile strength was measured according to A.S.T.M. procedures and thedata adjusted to account for differences in density, etc., in order toproyide an accurate comparison between felts.

'- Table I shows that under comparable conditions articles produced fromcontinuous filaments according-to the present invention have propertiessuperior to wool felts or synthetic felt-like articles formed fromneedlepunched staple batts (even though retracted).

t EXAMPLE v Following the procedure of theabove two examples, abatt'with linear azimuthal orientation of the filaments abrasion;resistance,as. by decreasing molecular-vorientav, tionof thefilaments.'.,.: .1. L

Thecompactnessand strength oflthe-product o invention 'are not dependentupon ,interfiber ,adhesion'om softening and vpartial fusion; In fact,s'uchifufsionlisiuu-i;

by the subsequentfretraction by treatment with heatuoii" a swellingagent. The original: degreexofLmol'eculm'i orientation, usually largelythe result. of..drawing,: may; be adjusted for a given use, With dueregard to..the .d sired resulting fiber elongation andtenacity'andithetin-l fluencei of draw ratioupon'retractabilityofthepatticui lar synthetic filamentary materialused;.111;

Felt-like materials of substantially-any desired'cha'm acteristics maybe formed according to this invention; Thus, rather than the type ofproduct determining utility,

as so often happens, here the products-of theiinvention may be made soasto fill a wide variety. of uses fornon woven materials These felt-likematerials may be. manufactured in suitable form for use as wet and dryfelts; filter media, carpets and their underliner's, insulation;

sound absorbents, chemical-resistant work l'c'lotlies, and a many otherindustrial and apparel uses. The transverse and longitudinal propertiesmay be made 'practically identical by blending or layering,or. widedifferences be-i tween them may be secured by sufficient. orientation ofthe starting filaments orfibers. The shape ofthe:prod uct may bedetermined by placing the battagainst-or around a fixed form so that thebatt assumesthei con figuration of the form during retraction,and-pressing may be used to improve shape correspondence in 'thisprocess modification. i r

Any synthetic organic continuousIfilamentary ma; terial is suitable foruse in the practice of inven tion By continuous, as used herein, .ismeantJafiy length greater than about eight inches. Preferably,- con-.tinuous filaments having anaverage length greater than about eightinches are employed 'becausefneedling ofya loose batt of predominantlysynthetic organic filamen'tary material having an average length ofat'least about .eight inches results in contraction of the batt,thereby-' producing a strong coherent felt-like productwithout recourseto retracting the batt. Thus, merely needle-punching of about 90diiferencebetween layers is constructed from high-tenacity rayon yarn(Super Cordura) hav-' ing a total denier of 1650, with 720filamentswWith the needle loam and barbed needles of Example III thisbatt is punched three times from one side at a needling frequency of 30penetrations per square inch during each pass. The batt is tripled bylaying up three plies and punched for an additional 8 passes,alternately from each side, i'receiving' 120 penetrations 'per squareinch The, batt contracted about 12% durinvention, and the retractionstep: required {to render staple batts felt-like is renderedunnecessarylThe steps of crimping synthetic staple and carding synthetic stapleorwool" also are-obviated. Retraction is an optional final step in thepractice of'the present invention; with some F materials *(eg; nylon)retraction tr'eatment":ad

vers'ely affects desirable characteristics of toughness and I tain,predominantly Icontinuous filament's, and theseafter" ncedlingr a loosebatt of continuous, filamentary material ineaccoidance with thisinvention without'chemi ca l or heat treatment decreases the surfacearea of thebatt as con trasted with an increase in surface area when 'a'loose' batt of conventional staple fibers is needle-punched ilfdesired, blends with animal, vegetable, or mineral continuousfilamentary material maybe employed although it is preferred to utilizesynthe tic 'organic continuous filaments alone. Of'course, morethanonekind of fiila-l ment may be blended or layeredto'g'ether 'It'will;'be'- appreciated that. needling ofia batt of continuous fila ments,will result in breakingof some filamentsand that V the product producedmay contain'a considerable num ber of broken filamentsdependiug upon theamount f needling. In all case's,';howe'ye'r, fthe product.wi lcon?ments will besynthetic' and organic in character. a I Most syntheticorganic continuous filaments can be' produced retractable rem foru seaccording to a pro fen-ed embodiment; of invention in "which addition;al compactness isfindnc'ecl by retracti'ng 'the mama-fits I Assuggested, thefretractionj' treatnient may consist ofheatingbyvariousmean shy-applies: tion of Water,"oil,' steam," airorother fluid whicltl is relatively inert 'with respect to theparticular filamutary'ma terial or it may involve exposure:of-"theLniaterial 102 a swelling agent in addition to'orlin place:ofothecheat treatmentI: A combination, of chemicaljandphysical;

For light-weight i mated treatments may be used, mild acid and alkalibaths being examples of what often may be acceptable chemicaltreatments. Any method of shortening the end-to-end length of thefilamentary material without too adversely affecting filament propertiesand fibrous structure is acceptable. If the filaments are to beretracted in a liquid bath, instead of by heating, a conveyor belt maybe arranged to carry the batt through a tank where the filaments aresubmerged in or sprayed with the retraction-inducing liquid. This may befollowed by suitable means for removing the liquid, such as wringerrolls and a drier, or by extraction, as will be understood in the art.The time of treatment may vary from a few seconds to hours, although forsimplicity, times of the order of a minute or so are preferred. Eitherretracted or unretracted products of this invention can be pressed forsmoothing of the surface or additional compaction of the filaments, ifdesired. Where a retracted batt is desired, it is preferred that thefilamentary material utilized be retractable in length to the extent ofat least about 15% in order to achieve substantial benefits from theretraction step.

In addition to the uses mentioned above for the products of thisinvention may be mentioned body armor and flak curtains, shaft packing,reinforced plastics, laminates, polishing felts, grease seals, wickingfelts, mechanical felts, wet and dry papermakers felts, apparel felts,artificial leather, sanforizing blankets, tire cord fabrics, steamingpads, roll covers, and shock and vibration mountings. Many othersuitable uses for these products will become apparent to anyoneundertaking to practice the present invention.

In general, the continuous filament needled, unretracted felt-likearticles of this invention possess superior abrasion resistance,chemical resistance, thermal stability, and tenacity to felt-likearticles made from staple fibers.

This application is a continuation-in-part of application Serial Number312,067, filed September 29, 1952, now abandoned, by Herbert G.Lauterbach and Harry M. Norton, and application Serial Number 436,014,filed June 11, 1954 by Herbert G. Lauterbach.

The claimed invention:

1. A non-woven coherent felt-like article comprising predominantlysynthetic organic continuous filamentary material characterized bypredominantly coplanar superimposed layers of the filamentarycomponents, the filaments in each layer being oriented at an anglerelative to adjacent filaments in adjacent layers, with portions of someof the filamentary components from each layer oriented into at least oneadjacent layer.

2. The product of claim 1 in which the continuous filamentary componentsare at least partly retractable to diminished length.

3. The product of claim 1 in which the filamentary material is apolyamide.

4. The product of claim 1 in which the filamentary material is rayon.

5. The product of claim 1 in which the filamentary material is apolyester.

6. The product of claim 1 in which the filamentary material ispolytetrafluoroethylene.

7. A non-woven retracted coherent felt-like article comprisingpredominantly synthetic organic continuous filamentary materialcharacterized by predominantly coplanar superimposed layers of thefilamentary components, the filaments in each layer being oriented at anangle relative to adjacent filaments in adjacent layers, with portionsof some of the filamentary components from each layer oriented into atleast one adjacent layer.

8. The product of claim 7 in which the filamentary material ispolyethylene terephthalate.

9. The product of claim 7 in which the filamentary material ispolytetrafluoroethylene.

10. The product of claim 7 in which the filament material is apolyamide.

11. A process for preparing a non-woven coherent felt-like articlecomprising forming a loose batt of predominantly synthetic organiccontinuous filamentary material as a plurality of superimposedsubstantially parallel layers, the filaments in each layer beingoriented at an angle relative to adjacent filaments in adjacent layers,and forcibly orienting portions of some of the filamentary componentsinto at least one adjacent layer.

12. The process of claim 11 in which substantially all of the continuousfilamentary material is retractable.

13. The process of claim 12 in which the felt-like article produced isretracted.

14. The process of claim 12 in which the filamentary material ispolyethylene terephthalate.

15. The process of claim 12 in which the filamentary material ispolytetrafluoroethylene.

16. The process of claim 12 in which the filamentary material ispolyhexamethylene adipamide.

17. The process for preparing a felt-like product which comprisesforming a mass of heat retractable continuous synthetic filaments into aloose batt, said filaments being retractable by at least 15% in lengthwhen heated below the fusion temperature, punching portions of some ofthe filaments into the batt in a direction substantially perpendicularto the faces of the batt, and then without other treatment heating thefilaments so that they retract at least 15% in length and remain free tomove over each other though under frictional constraint from mutualcontact until they retract sufiiciently to compact the batt to afelt-like product.

18. The process for preparing a felt-like product which comprisesforming a mass of heat retractable substantially continuous polyethyleneterephthalate filaments into a loose batt, said filaments beingretractable by at least 15% in length when heated below the fusiontemperature, punching some of the filaments for part of their lengthinto the batt in a direction substantially perpendicular to the faces ofthe batt, and then without other treatment heating the filaments belowthe fusion temperature to cause them to retract at least 15 in lengthwithout adhering with resulting compaction of the batt to a felt-likeproduct.

References Cited in the file of this patent UNITED STATES PATENTSFrancis Mar. 16, 1948

1. A NON-WOVEN COHERENT FELT-LIKE ARTICLE COMPRISING PREDOMINANTLYSYNTHETIC ORGANIC CONTINOUS FILAMETARY MATERIAL CHARACTERIZED BYPREDOMINANTLY COPLANAR SUPERIMPOSED LAYERS OF THE FILAMENTARYCOMPONENTS, THE FILAMENTS IN EACH KAYER BEING ORIENTED AT AN ANGLERELARIVE TO ADJACENT FILAMENTS IN ADJACENT LAYERS, WITH PORTIONS OF SOMEOF THE FILAMENTARY COMPONENTS FROM EACH LAYER ORIENTED INTO AT LEAST ONEADJACENT LAYER.